Geothermal energy control system and method

ABSTRACT

A geothermal energy transfer and utilization system makes use of thermal energy stored in hot solute-bearing well water to generate super-heated steam from an injected flow of clean water; the super-heated steam is then used for operating a turbine-driven pump at the well bottom for pumping the hot solute-bearing water at high pressure and in liquid state to the earth&#39;s surface, where it is used by transfer of its heat to a closed-loop boiler-turbine-alternator combination for the generation of electrical or other power. Residual concentrated solute-bearing water is pumped back into the earth. The clean cooled water is regenerated at the surface-located system and is returned to the deep well pumping system also for lubrication of a novel bearing arrangement supporting the turbine-driven pump system.

CROSS REFERENCE TO RELATED CASES

The following applications employ the same drawings and description ofthe preferred embodiments as are used in the present application,claiming different features of the apparatus disclosed therein and areassigned to Sperry Rand Corporation:

H. b. matthews, K. E. Nichols, Ser. No. 487,429, filed July 10, 1974 for"Geothermal Energy System and Control Apparatus,"

J. l. lobach, Ser. No. 488,331, filed July 15, 1974 for "GeothermalEnergy Turbine and Well Structure," R. Govindarajan, J. L. Lobach, K. E.Nichols, Ser. No. 488,333, filed July 15, 1974 for "Geothermal EnergyPump Thrust Balance Apparatus".

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to efficient means for the generation ofelectrical or other power utilizing energy from geothermal sources and,more particularly, relates to arrangements including efficientsuper-heated steam generation and pumping equipment for application indeep, hot water wells for the transfer of thermal energy for use at theearth's surface.

2. Description of the Prior Art

While geothermal energy sources have been employed for the generation ofpower to a limited extent, generally known prior systems operate atrelatively low efficiency and have serious disadvantages. In therelatively few installations in which substantially dry steam issupplied by wells at the earth's surface, the steam may be fed, afterremoval of solid matter, from the well head directly to a turbine. Onthe other hand, most geothermal wells are characterized by yields of amixture of steam and hot water containing corrosive solutes at theearth's surface, so that the water must be separated from the steambefore the latter is used in a turbine.

In both of these kinds of installations, relatively low pressure steamnormally results, requiring special turbines and yielding relativelyinefficient power generation as compared to generation of power usingnormally operated fossil fuel-powered or nuclear-powered electricalgeneration equipment. In only a few instances do geothermal wellsactually produce truly super-heated steam with only minor amounts ofundesired gasses and with no liquid water.

The presence of significant amounts of liquid water in wells used withprior art geothermal systems presents other problems in addition to theseparation problem. If the water is only moderately hot, extractingthermal energy from it may be expensive or, at least, inefficient.Whether or not the heat is used, the water must be handled. The waterusually bears considerable concentrations of silica and of alkali salts,including chloride, sulfate, carbonate, borate, and the like ions, allof which dissolved salts present precipitation problems at the point atwhich any part of the water may abruptly flash into steam. If thealkaline water is allowed to escape at the installation, severe chemicaland thermal pollution of streams or rivers may result. Finally, there issome evidence that the removal of large amounts of water from geothermalreservoirs may lead, in a generally unpredictable manner, to undesirableland subsidence in the vicinity of thermal well installations.

A major advance in the art of extraction and use of geothermal energy isreflected in the H. B. Matthews U.S. patent application Ser. No. 300,058for a "Geothermal Energy System and Method," filed Oct. 24, 1972 issuedJuly 23, 1974 as U.S. Pat. No. 3,824,793, and assigned to the SperryRand Corporation. The prior Matthews invention provides means forefficient power generation employing energy derived from geothermalsources through the generation of dry, super-heated steam and theconsequent operation of sub-surface equipment for pumping extremely hotwell water at high pressures upward to the earth's surface. Clean wateris injected at a first or surface station into the deep well wherethermal energy stored in hot solute-bearing deep well water is used at asecond or deep well station to generate super-heated steam from theclean water. The resultant dry super-heated steam is used at the wellbottom for operating a turbine-driven pump for pumping the hotsolute-bearing well water to the first station at the earth's surface,the water being pumped at all times and locations in the system atpressures which prevent flash steam formation. The highly energeticwater is used at the surface or first station in a binary fluid systemso that its thermal energy is transferred to a closed-loopsurface-located boiler-turbine system for driving an electrical poweralternator. Cooled, clean water is regenerated by the surface system forre-injection into the well for operation of the steam turbine therein.Undesired solutes are pumped back into the earth via a separate well inthe form of a concentrated brine.

In contrast with the relatively poor performance of other prior artsystems, the prior Matthews invention is characterized by highefficiency as well as by many other advantageous features. It is notlimited to use with the rare dry steam sources, and it is devoid of thewater and steam separation problems attached to the more usual prior artsystems used with mixed steam and hot water supply wells. Since thenovel power system operates with dry, highly super-heated steam,existing efficient heat transfer elements and efficient high pressureturbines may readily be employed. According to the invention, the verylarge calorific content of high temperature water subjected to highpressure is efficiently employed. Since high pressure liquid is used asthe thermal transfer medium, undesired flash steam formation isprevented, along with its undesired attendant deposition of dissolvedmaterials. Because the dissolved salts are efficiently pumped back deepinto the earth as remotely as need be from the geothermal source,surface pollution effects are avoided and there is relatively littlerisk of land sinkage in the vicinity of the geothermal source.

SUMMARY OF THE INVENTION

The invention is an improvement in deep well geothermal systems of thekind described in the aforementioned U.S. Pat. No. 3,824,793; accordingto the present invention, there is provided an efficient means for thegeneration of electrical power at the earth's surface, using energyabstracted from the geothermal source. The apparatus includes means forthe efficient generation of super-heated steam and a steam drivenpumping system at the well bottom operated for transfer of hot water tothe earth's surface where its energy content is beneficially used forpower generation.

According to one feature of the invention, the deep-well steam turbineand pump arrangements are supported in a novel system of hydrodynamicthrust and radial bearings with all bearing surfaces fully bathed inclean water serving as a lubricant and maintained under pressure so asto prevent entry of the corrosive and contaminated hot well water andthe consequent ultimate destruction of bearing surfaces. Alternatively,a bearing configuration employing hydrodynamic bearing elements may beemployed. A thrust ball bearing arrangement is provided that normallycomes into play only when starting or stopping the turbine-hot waterpump system. A further feature of the invention permits use ofsurface-located apparatus for assuring efficient continuous operation ofthe power generation system and also enables controlled starting andstopping of the subterranean steam turbine-pump apparatus. A furtheraspect of the invention permits efficient steam generation in a confinedannular volume lying between concentric vertical tubes; the featurecauses a spiralling downward flow of steam and of the diminishingpopulation of water drops so that they both flow in close proximity tothe hottest of the two tubes, thus improving the efficiency of steamformation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view, mostly in cross section, of the novel deepwell geothermal pumping apparatus of the system.

FIGS. 2 and 3 are detailed elevation views in cross section of portionsof the apparatus of FIG. 1.

FIG. 4 is a plan view of an element of the FIG. 3 apparatus.

FIG. 5 is a detailed cross section view taken along the line 5--5 ofFIG. 4.

FIG. 6 is a developed drawing partly in cross section of a portion ofthe FIG. 3 apparatus.

FIG. 7 is a detailed elevation view in cross section of the lowerportion of the apparatus of FIG. 1.

FIG. 8 is a developed drawing of a portion of the apparatus seen in FIG.7.

FIG. 9 is a cross section view of a hydrodynamic bearing system for usein the apparatus of FIG. 7.

FIG. 10 is a plan view in cross section taken along the line 10--10 ofFIG. 9.

FIG. 11 is a plan view in cross section taken along the line 11--11 ofFIG. 9.

FIG. 12 is an exploded view, partly in cross section, of part of thebearing system of FIG. 9.

FIG. 13 is a plan view taken along the line 13--13 of FIG. 9.

FIG. 14 is a cross section view of a hydrostatic bearing systemalternative to that of FIG. 9.

FIG. 15 is a diagrammatic representation of the apparatus at the earth'ssurface cooperating with the deep well apparatus of FIG. 1.

FIG. 16 is an elevation view in partial cross section of the regulatordevices shown in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates the general structure and characteristics of thatportion of the novel geothermal energy extraction system which isimmersed in a deep well extending into strata far below the surface ofthe earth, preferably being located at a depth below the surface suchthat a copious supply of extremely hot water under high pressure isnaturally available, the active pumping structure being located adjacentthe hot water source and within a generally conventional well casingpipe 10. The configuration in FIG. 1 is seen to include a well headsection 1 located above the earth's surface 11 and a main well section 2extending downward from well head section 1 and below the earth'ssurface 11. At the subterranean source of hot, high pressure water, themain well section 2 joins a steam generator input section 3. The steamgenerator section 4, the steam turbine section 5, a power plant rotarybearing section 6, and a hot water pumping section 7 follow in closecooperative succession at increasing depths.

Extending downward from the well head section 1 at the earth's surface11, the well casing pipe 10 surrounds in preferably concentric relationan innermost stainless steel or other high quality alloy steel pipe orconduit 8 for supplying a flow of relatively cool and relatively purewater at the bottom of the well for purposes yet to be explained. Asecond relatively large pipe or conduit 9 of similar quality andsurrounding pipe 8 is also provided within well casing 10, extendingfrom well head 1 to the energy conversion and pumping system at thebottom of the well and permitting turbine exhaust steam to flow to thesurface of the earth, as will be described.

It will be seen from FIG. 1 that relatively clean and cold water ispumped down the inner pipe 8 from the surface 11 station to the regionof the pipe tee 12. At tee 12, the downward flowing water is dividedbetween two branch paths. As will be described, a first branch pathfeeds clean lubricating water through pipes 13 and 17 for lubricating asystem of bearings within the system bearing section 6. The secondbranch path feeds clean water through pressure regulator system 15 andvia distribution pipe or pipes 16 to the input manifold 22 of a steamgenerator 18 formed between the generally concentric walls of alloypipes 9 and 9a. Accordingly, high pressure steam is generated anddelivered to a steam turbine located within turbine section 5.

The function of the turbine located at 5 and supported on bearingslocated within bearing section 6 is to drive a hot water pump located atsection 7. Hot, high pressure water is thus impelled upward by therotating pump vanes 20 between the rotating conical end 23 of the pumpand an associated rotating or stationary shroud 19; the hot water ispumped upward at high velocity in the annular conduit between pipes 9and 10, thus permitting use of the thermal energy it contains at theearth's surface, as will be described. More important, the hot water ispumped upward to the earth's surface 11 at a pressure preventing it fromflashing into steam and thus undesirably depositing dissolved salts atthe point of flashing.

Accordingly, it is seen that the extremely hot, high-pressure well wateris pumped upward, flowing in the annular region defined by alloy pipes 9and 10. Heat supplied by the hot well water readily converts the cleanwater flowing into manifold 22 of the steam generator 18 into highlyenergetic, dry, super-heated steam. The clean water, before flowingthrough tee junction 12 and pressure regulator 15, is at a very highpressure due to its hydrostatic head and usually also to pressure addedby a surface pump yet to be discussed, so that it may not flash intosteam. The pressure regulator system 15 controls the pressure of theclean water flowing therethrough so that it may be vaporized andsuperheated in the volume 18 of the steam generator. The highlyenergetic steam drives the steam turbine and is redirected to flowupward to the surface 11 after expansion as relatively cool steamflowing within the annular conduit defined between alloy pipes 8 and 9.Thermal energy is recovered, as will be discussed, at the earth'ssurface 11 primarily from the hot, high pressure water, but may also beretrieved from the turbine exhaust steam.

Referring now to FIG. 2, certain details of a preferred form of thesteam generator input section 3 and of the steam generator section 4 areillustrated. The general configuration is seen to be similar to thatdescribed in connection with FIG. 1. However, in FIG. 2, the teejunction 12 is used to feed two pressure control or regulator devices, apressure threshold valve 15a in series with which is a differentialpressure valve 15b. Both valves may be generally conventional, or may bemodified as will be further discussed in connection with FIG. 16.Threshold valve 15a depends for operation upon sampling the pressure ofthe rising hot water stream between pipes 9 and 10, and the connectinghollow tube 21 is therefore provided for this purpose. Also, theconfiguration of FIG. 2 additionally illustrates a symmetric inputsystem for the steam generator 18. For this purpose, an array ofradially directed distribution pipes 16 is supplied for conducting thepressure regulated water output of differential pressure valve 15bthrough apertures in steam generator end plate 29 into the interior ofgenerator volume 18. In this manner, clean water is symmetricallydistributed to the annular steam generator 18 where a fraction of theintense heat content passes from the pumped hot water through the wallof pipe 9 for producing the super-heated, dry steam.

The alloy pipes 9, 9a are spaced apart and are supported in fixedrelation by arrays of radial spacers, such as the representative spacers31, 31. The spacers 31, 31 may be aligned vertically and it isunderstood that several such arrays of spacers will preferably be usedat intervals along the steam generator walls. In a preferred form of thespacers, they are shaped so that they perform an added function. Asnoted in the foregoing, fresh water supplied by manifold 22 is convertedto super-heated steam as it travels downward in the steam generatorannulus 18. In certain applications, it is found that an undesirableproportion of water drops fall through the steam generator volume 18without being fully vaporized. Since such water drops are more densethan the dry steam, they travel downward much faster than the alreadyvaporized portion of the flow and therefore tend to stay generally atthe center of the flowing stream, not impacting the heated surface ofpipe 9 where heat transfer is high. In the steam generator 18, there isalso an additional complication in that the two-phase stream is flowingdownward in an annulus and the inside surface of that annulus (providedby alloy pipe 9a) tends to absorb heat rather than contributing thermalenergy to the steam generation process. The heat absorption mechanism isconnected with the fact that the rising fluid within pipe 9a isrelatively cool turbine exhaust steam. To overcome this undesiredresult, arrays of spacers such as 32, 32, 32 may be employed; thespacers 32 are no longer vertical, but are shaped and are oriented atfinite angles with respect to the vertical. It is understood thatseveral such arrays of spacers 32 will normally be used at intervalsalong the surface 9a. While the character of the shaping and the averageskew angle will depend upon general design considerations, the curvedspacers are arranged to swirl the down-flowing dual-phase fluid intogenerally helical paths, as illustrated by arrow 33. In this manner, theaction of centrifugal force tends to force both the water drops and thealready converted steam toward the heat source represented by thecontiguous surface of pipe 9 and away from the heat sink represented bythe contiguous surface of the cooler pipe 9a. The advantageous resultsare that the previously converted steam is further heated and that anywater drops are converted to steam also further heated as it passes downthe steam generator volume 18 toward the steam turbine.

It will be appreciated from FIG. 1 that a severe problem to be solved indevising practical forms of the invention lies in creating aconfiguration which is compact, as well as efficient, especially in viewof the consideration that the operating structure is preferably to beinserted into a well casing of standard size. Compactness of thestructure, as well as efficiency of operation are therefore primefeatures of the apparatus of FIGS. 3 through 6, which apparatus is foundwithin the turbine structure section 5 of FIG. 1.

Referring particularly to FIG. 3, it is seen that the conduits of FIG. 2extend into the steam turbine section 5. For example, the pumped hotwater passage is located between pipes 9 and 10, while opposed surfacesof pipes 9 and 9a define the steam output passage 18 of the steamgenerator. Between pipes 9a and 17 is the passage for upward flowingexhaust steam from the turbine. The pipe 17 is effectively extended topermit downward flow of clean water into and past the steam turbinesection 5 via the channels 40 and 41. It is seen that a series of radialspaced vanes 34 welded between pipes 9a and 17 provides a supportingfunction; within the rising exhaust steam chamber, they additionallytend to redirect the exhaust steam so that it flows in a verticaldirection without any substantial rotational motion.

For operating the steam turbine of FIG. 3, the steam from the steamgenerator 18 between pipes 9 and 9a is injected into an annular manifold42, from whence it flows into an array of steam injection nozzles at 43of generally conventional design. The nozzles 59 are shown in moredetail at 43 in the developed view of FIG. 6 and are employed in theconventional manner to direct the high velocity steam against the bladesof the turbine stages.

Single or multiple stage turbine blade systems of various known typesmay be employed in the system. However, for purposes of illustration, amultiple stage arrangement is presented, first and second stages beingprovided by respective pluralities 44 and 46 of vanes which pend incircular arrays from a circular base ring 47. The rotor arrays of vanes44 and 46 cooperate with an intermediately located conventional array 45of stator vanes affixed to the body block 74 common to the turbinesection 5 and bearing section 6. The ring 47 bearing the vane arrays 44and 46 is affixed in a conventional manner to a wheel rim 48. Rim 48 ispart of a wheel additionally provided with a set of spokes 54 and a hub49. Hub 49, when the rotor system is rotating, causes shaft portions 50and 58 also to rotate, the hub 49 being securely fastened on shaftportion 50 by washer 51 and nut 52 secured on the threaded extension 53of shaft portion 50.

A feature of the invention permitting compactness of design is concernedwith the disposal of expanded steam which has yielded useful energy tothe turbine rotor; the feature solves the particular problem ofredirecting the exhaust steam without the requirement of space consumingelements. For this purpose, the turbine body block 74 contains anannular smoothly curved toroidal passageway 56 which redirects steamissuing from the rotary vane array 46 radially inward towards shaftportion 58, at the same time altering its direction so that the steam iscaused to flow upwardly. The annular passageway 56 is defined by asuitably curved surface 60 cast within the body block 74 and by thesurface of the opposed annular ring or guide 55. Ring guide 55 may besupported by an array or radially extending vanes 57 which, in additionto supporting the ring guide annulus 55 with respect to turbine bodyblock 74, also tend to redirect the exhaust steam so that its velocityis primarily vertical, rotational components of motion being reduced inamplitude. Accordingly, it is seen that there is formed a smooth-sidedtoroidal steam expanding passageway directing the steam after it exitsthe annular vane array 46 until it passes again through the turbinewheel.

The passage of steam through the latter is particularly facilitated byarranging the spokes 54 of the turbine wheel as illustrated particularlyin FIGS. 4 and 5 so that the steam passes through the wheel, in essence,as if the spokes 54 were not present. The spokes 54 are individuallytilted with respect to the direction of the rotation of rim 48 so thattheir effect at the selected operating rotational speed of the rotor isentirely neutral. In fact, spokes 54 are shaped and are provided with anangle of incidence with respect to the direction of steam flow so thatthey desirably neither add energy nor subtract energy from the upwardflowing steam. Further, steam passages outside of the periphery of therotating element of the steam turbine are not required and the resultantblocking of the flow of the pumped hot well water is avoided. Aspreviously noted, it will be apparent to those skilled in the art thatalternative features of known steam turbines may be employed within thescope of the invention. By way of further example, a double-stagere-entry turbine may be employed in which the steam is passed downwardthrough one set of nozzles of a turbine having a single array of bladesand is then reversed to flow upward through a second set of nozzles andthe same turbine blades, the used steam again being exhausted in thegeneral direction indicated in FIG. 3.

FIG. 7 illustrates particularly the relations of elements of the bearingsupport system 6 and of the hot water pump section 7. With reference toFIG. 3, it is seen that there extends into the apparatus of FIG. 7 thewell casing 10 and the bearing or body support block 74 from which issupported by bolts such as bolt 69 a generally conical casting 75supporting, in turn, the pump apparatus, as will be further described.The castings or blocks 74 and 75 perform several primary functions,including providing a casing for containing the bearing systemcooperating with and surrounding the shaft by means of which the steamturbine directly drives the hot water pump. However, for the purpose ofproviding clarity in the drawings, the bearing system will be discussedseparately, especially in connection with FIG. 9. With reference to thatdiscussion, it will be seen that clean lubricating water is suppliedthrough body block 74 via passage 41, annular manifold 73 and thepassage or passages 73a to the bearing system. Further, it will be seenthat fasteners such as 72 and 76 position certain elements of thebearings relative to casting blocks 74 and 75.

A hardened case is provided to integrate and protect blocks 74, 75 fromimpact and corrosion and takes the form of a circular element having ahollow cylindrical portion 70 and a truncated hollow conical shellsection 71 extending downward in concentric relation with the conicalend portion of block 75. The pump end of shaft portion 68 projectsbeyond the generally co-planar ends of conical shell section 71 andconical block 75 for supporting conical end rotor 77 whose conical sidesare, in effect, extension of the conical surface 89 of conical shellelement 71. It will be seen that the nose cone rotor 77 supports otherrotary elements of the pump, including a plurality of pumping vanes,such as vane 20, and a rotatable section 84 of the pump shroud.

Several fixed shroud elements cooperate with the rotatable shroudelement 84. These include particularly a generally cylindrical shroudelement 93 having an upper conical surface 82 generally of the form ofthe contour of conical surface 89. The annular shroud element 93 issupported directly from surface 89 by a plurality of stationarystream-directing vanes 80. The vanes 80 act both to support shroudelement 93 and also to direct the flow of the pumped hot water. Whilethe vane 80 is illustrated in FIG. 7 as lying generally in the plane ofthe drawing, the vanes 80 are preferably shaped so as to efficientlyconvert any rotational component of motion of the pumped hot water intoupward translation, thus increasing the hot water high pressure as itascends. The stator part 93 of the shroud is completed by a throatmember 85 of annular construction held in place against shroud element93 by an array of bolts such as bolt 87. There is thus defined withrespect to mouth 88 of the pump, the inner curved surfaces of shroudthroat element 85 and of rotatable shroud element 84, and conicalsurfaces 82 and 89, a passageway by means of which the hot, highpressure water is directed upward at a significantly high velocity forflow within the casing 10. As noted in the foregoing, the plurality ofvanes 20 supports rotary shroud element 84 from nose cone 77 for highspeed rotation by shaft section 68. While the impeller vanes 20 areshown in the figure as having generally flat plane surfaces, they willpreferably take on the hydrodynamic but conventional curved shape shownat 20 in the developed drawing of FIG. 8 for most efficient cooperationwith the stationary vanes 80. Flow of hot well water between casing pipe10 and the stator section 93 of the pump shroud is prevented in anyconvenient manner, as by use of an annular seal 90 adjacent the pumpmouth 88.

Novel features of the invention provide a thrust balance mechanism inthe hot water pump configuration. Significant downward axial thrust isencountered with respect to the turbine pump shaft due to the pressurehead rise generated by the pump when impelling the hot water upward,this thrust being nearly proportional to total dynamic pressure.Ordinarily with systems in which considerable space is available, largethrust bearings would be employed to carry the large maximum anticipatedload. However, such bearings, when used under the present set of hostilecircumstances, would be characterized by high levels of power loss andlong life and efficiency could certainly not be expected.

The need for finding a mechanism for balancing the high downward axialthrust may be illustrated in a general manner by a specific example. Theoffered specific example is merely for illustrative purposes, and thevalues given are not necessarily exact examples of values that would beemployed in actual practice.

Consider, for example, that the hot well water pressure at the mouth 88of the pump throat is about 800 pounds per square inch. In the operatingcondition of the pump, the pressure in the volume occupied by theimpeller vanes 20 would be boosted, for example, to 1050 p.s.i. At thelocation at which stator or diffusion vanes 80 meet the annulus 81between casing 10 and the hollow cylinder portions 70, the pressuremight be found to be 1150 p.s.i.

When the turbine and pump system is rotating at its intended operationalspeed, it generates a heavy downward thrust at shaft portion 58 which isnormally opposed by the upward thrust of the 800 p.s.i. hot well wateragainst the equivalent area of the shafts. There remains a considerablenet downward force which would otherwise require a large thrust bearingto be absorbed. The pressure balance arrangements of FIG. 7 reduce theundesired net downward thrust and thus permit reduced size of the thrustbearings, which bearings will be discussed relative to FIGS. 9, 12, 13,and 14.

A first aspect of the system for reducing the net downward shaft forceinvolves the configuration of the conical rotor or hub end 77. Rotor hub77 is arranged with a relatively large axial bore 78 and with alabyrinthal seal 79 lying generally in a horizontal plane in closeproximity to cooperating labyrinth seal elements on the generallyhorizontal end of the stationary conical casting block 75. The elementsof seal 79 are concentric with shaft end portion 68 and may consist ofmany concentric ring-shaped labyrinthal elements as is well known in theart, being shown with only a single stage merely for convenience andclarity in the drawing. Thus, hot water may flow axially with respect tobore 78 and radially in the narrow passageway of labyrinth seal 79.

In the absence of the cooperative presence of bore 78 and labyrinthalseal 79 there would, according to the foregoing example, be a pressureat the top of conical end rotor 77 of about 1050 p.s.i. or when theeffects of the differing areas of the shaft and end rotor 77 areconsidered, there would be a downward thrust of 6000 pounds. In theconfiguration shown in FIG. 7, labyrinthal seal 79 allows only a smallamount of hot water flow from the 1050 p.s.i. annulus region 80 radiallyinward to the top center of rotor hub 77. The high impedance passage waythrough seal 79 and the low impedance represented by bore 78 cooperateso that the pressure on top of hub 77 is essentially 800 p.s.i., ratherthan the former 1050 p.s.i., reducing the net downward thrust by 920pounds. It is noted that the area of the labyrinthal seal 79 is at apressure intermediate between 800 and 1050 p.s.i., for example.

The second aspect of the system for reducing the downward thrust on theshaft is incorporated in the pump shroud system including shroud statorelements 85, 93 and the shroud rotor element 84, which latter is affixedto and rotates with the pump impeller vanes 20. The interface betweenthe shroud rotor section 84 and the stator shroud elements 84 and 93accommodates a pair of cooperating annular labyrinthal seal elements 91and 92. Intermediate the distinct seal sections 91, 92 are openings topassageways 83 connecting to the annular passageway just within casingpipe 10 at a junction tapping the 1150 p.s.i. pressure within pipe 10.The labyrinth seal at 91 has a significantly larger diameter than thatof labyrinthal seal 92. The elements of the separated labyrinthal seals91, 92 will, in usual practice, consist of a conventional plurality ofcooperating ring-shaped labyrinth elements.

In view of the passageways 83, there will be a differential pressure,say 100 p.s.i., developed across the seal 91. This differentialpressure, acting upward on the differential areas of seal 91 and seal 92establishes an upward thrust, for instance, of 380 pounds, further tohelp counteract the downward thrust of the operating pump. Thus, thefirst and second components of the thrust compensation system greatlyreduce the forces on the thrust bearing system yet to be discussed andtherefore, a relatively smaller diameter thrust bearing may be employed.By use of the two balancing features, reliability of operation isassured along with minimal losses. The axial thrust and balancing forcesare both proportional to the pump discharge pressure, so that thebalanced condition prevails over a range of speed and flow conditions.

As previously noted, the steam turbine and pump devices of FIGS. 3 and 7rotate on a shaft whose details are more completely illustrated in FIGS.9 through 13. Referring now particularly to FIG. 9, the shaft is seen toproject through the bearing section 6 between the steam turbine whoserotor is affixed to shaft portion 50 and the water pump whose rotor isattached to shaft portion 58. In general, it is seen that the bearingsupport structure in bearing section 6 involves four primary elementsand that these include a first radial bearing arrangement cooperatingwith the enlarged shaft portion 61, a thrust bearing section cooperatingwith the enlarged and tapered section 125, a ball bearing section 154provided for intermittent use, and a second radial bearing arrangementcooperating with the enlarged shaft portion 94. It will be understoodthat the turbine-pump shaft bearings are continuously bathed in cleanwater injected through passage way 73a seen also in FIG. 7 connected toannular manifold 73. The presence of corrosive and contaminated hot wellwater is prevented by the application of clean water under high pressureto all bearing surfaces. In general, the radial loads due to the shaftare relatively small and are accommodated by tilting pad hydrodynamicbearings associated with shaft portions 61 and 94. The large downwardthrust experienced, for instance, during operation of the pump isaccommodated by a tilting pad hydrodynamic thrust bearing associatedwith the tapered enlarged section 125, as will be further discussed inconnection with FIG. 12. A hydrostatic thrust bearing may be substitutedfor the hydrodynamic thrust bearing, as seen in FIG. 14.

It will be further understood that the ball bearing arrangement 154comes into play only when the shaft thrust is upward during zero or lowrotational speeds, a condition existing only during or before start upor after shut down. If a hydrostatic bearing similar to that at 125 wereinstead provided to accept this upward thrust, the rotational speedsexisting during this condition would not be sufficient to generate aseparating fluid film between the bearing surfaces, which wouldconsequently suffer damage or destruction. In an extreme case, the steamturbine might not be able to supply the torque needed to start rotationof the system against the frictional effects at the interface of thethrust pad bearings. Accordingly, the ball bearing system's primaryfunction is at the starting of the apparatus and immediately before itsrotation completely stops.

It will be noted that clean water flows through the passage 73a into allof the passageways within and around the several bearings, continuouslybathing the bearing surfaces with clean cool water. The water flowinginto the thrust bearing may flow, for example, between the tilt bearingplates 132 and 133 and will then flow upward through passageways such as123 and 122 into the radial bearing associated with bearing surface 61.It will lubricate the bearing elements there and will flow upward pastthe high impedance seal 106, being finally dissipated within the exhastof the turbine at 56. The annular seal 106 is held by retainer 105 in aconfined position and preferably is a seal having very small clearancewith respect to the cylindrical surface of shaft portion 50. Suchclearance seals are well known in the art and are available in themarket, being constructed of tungsten carbide or of aluminum oxide, forexample.

The water injected by passage 73a into the thrust bearing also flowsdownward into passage 144 surrounding shaft portion 128, thus flowingbetween the races 146, 147 of the ball bearing system 154. Accordingly,the bearing surfaces of the balls and of the races 146, 147 arecontinuously lubricated with clean water which flows on downward intothe radial bearing associated with shaft portion 94. The bearingsurfaces associated with this radial bearing are thus also continuouslylubricated with clean water, which is then permitted to flow past theannular high impedance seal 164 and is dissipated by flowing into thehot well water being pumped upward, as described in connection with FIG.7.

Referring now to FIGS. 9 and 10, the structure of the two radialbearings respectively associated with shaft portions 61 and 94 will bediscussed. Particularly referring to FIG. 10, it is seen that the radialbearing is of generally conventional tilting pad construction and thatthe shaft portion 61 is surrounded by a hollow cylinder 95 of aluminumoxide affixed to the shaft. In the usual instance, three tilting padsurfaces cooperate with the aluminum oxide cylinder 95, a typicalconstruction employing a fastener 72 including pad positioning shaft 101which resides in a bore in the body block 74. Pad positioner shaft 101is located according to the setting of its threaded portion 102,arranged for radial adjustment within body 74. Shaft 101 accommodates,at its opposite end, a hardened steel sphere 99 partially residing at acounterbore 100. Sphere 99 projects into the water filled interiorwithin cylindrical wall 97 of body block 74, where it thrusts against amating depression in the bearing support block 96. To its inner arcuatesurface is fixedly attached, as by brazing or other conventionalmethods, an arcuate sector 98 made of aluminum oxide. The sector 98 andthe cylinder 95 have contiguous surfaces between which there resides avery thin lubricating film of clean water. The cylindrical aluminumoxide element 95 may also be affixed to shaft 61 by brazing or by theuse of mechanical fixtures such as the annular flange 104 seen at thetop of FIG. 9. In practice, three or more similar tilting pad radialbearings are employed fully to establish the position of shaft portion61. It will be evident that the radial bearing at the portion 94 of theshaft in FIG. 9 may be similarly constructed and operated.

The thrust bearing system is located in FIG. 9 between the two radialbearings associated with shaft portions 61 and 94 and is shown in detailin FIGS. 9, 12 and 13. As seen particularly in FIG. 9, the tilting padthrust bearing system includes an enlarged and tapered section 125 forsupplying a horizontal interfacing surface 126. At the interface surface126 is fastened with a fluorocarbon viton bonding agent of commercialtype or is brazed or otherwise fastened a flat ceramic ring 129generally concentric with shaft portion 128. The exposed flat annularsurface 127 of ceramic ring 129, which may be composed of alumina, formsa thrust bearing surface. As in the instance of the radial bearing, thealumina employed may be of the grade known as COORS 995, which is 99.5percent pure aluminum oxide.

As seen most clearly in FIGS. 12 and 13, the flat bearing surface 127cooperates with a plurality of bearing surfaces, such as the surface ofbearing 130, each bearing 130 being associated with a tilt pad thrustbearing element. Each such tilt bearing pad comprises a truncatedsector-shaped metal base plate 131 to which the associated sector shapedceramic bearing 130 may be brazed or otherwise permanently affixed atinterface 135. The surface of ceramic bearing 130 is permitted to followclosely to the surface 127 of the annular ceramic ring 129 by amechanical system yet to be described cooperating with a sphericaldepression at 170 located centrally in the lower surface of metal baseplate 131.

To facilitate tilting of the plural ceramic bearings 130 with respect tothe annular support plate 134 as the surface 127 rotates, a pair of tiltbearing plates 132 and 133 is used. Tilt bearing plate 132 is providedwith a circular array of hardened spheres 171 providing hemisphericalbearing surfaces one each for the respective depressions 170. Whileceramic bearing 130 is prevented from rotating about sphere 171 becauseof the close proximity of the inner portion of bearing 130 to shaftportion 128, the surface of bearing 130 now has some of the degrees ofmechanical constraint needed to permit it to follow surface 127precisely.

Further undesired constraints are removed by tilt bearing plates 132,133. For this purpose, the upper tilt bearing plate 132 has attached inits lower surface a pair of diametrically located hemisphericaldepressions 172, 172. These depressions match the locations of hardenedspheres 173, 173 affixed at the upper surface of lower tilt bearingplate 133 so that the upper tilting plate may rotate or tilt slightlyabout the line between spheres 173, 173. In a similar manner, the lowertilting plate 133 is provided in its lower surface with hemisphericaldepressions 174, 174. Depressions 174, 174 are spaced along a diameterat right angles to the line between depressions 172, 172. Thus, theformer cooperate with hardened spheres 175, 175 (one of which is notseen in FIG. 12) affixed in the upper surface of support plate 134. Asseen in FIG. 9, the support plate 134 is clamped in fixed relationbetween the body block 74 and the conical casting block 75. Further, itis seen that elements 132, 133, and 134 are provided with centralaperatures through which the shaft projects for rotation and throughwhich clean bearing lubricating water passes. In this manner, the tiltbearing plates 132, 133 act in a limited range as elements of a gimbalsystem for permitting each bearing surface of the several ceramicbearings 130 seen in FIG. 13 to follow the flat annular surface ofceramic ring 129 with such precision that the separation between thebearing surfaces is maintained precisely by the supporting clean waterfilm.

FIGS. 9 and 11 illustrate an arrangement of parts made necessary becauseof tapered portion 125 to facilitate assembly of elements of theinvention. An annular element is formed in halves 121, 121a and is heldin position by pins or other fasteners 120 threaded as at 150 into amating threaded bore 151 in body casting block 74, the elements 121,121a simply largely filling a a space within body casting block 74 inwhich undesirable turbulence might occur in the clean lubricating water.Being generally conformal to the shape of its surrounding walls, thepassages 122, 123 are more narrowly defined by the annulus 121, 121a.

In the starting condition of the pump, there is a several hundred poundupward thrust against the main shaft because of the high pressure of thehot well water. The effect of the reverse thrust present in the startingor stopping situation must be reduced or removed, even though thestarting cycle may be, for instance, only a minute or so in duration.For this purpose, the ball bearing system 154 of FIG. 9 is interposed,by way of example, between the thrust bearing at the tapered shaftportion 125 and the radial bearing at shaft portion 94. In FIG. 9, theball bearing system 154 is shown in its actual operating situation, as,for example, during start up or shut down of the entire apparatus. Insuch a situation, the hot well water pressure forces the shaft upward,so that the upper surface 148 of the enlarged shaft portion 94 is forcedagainst a surface of retainer 150. Its outer race 146 is affixed toouter annular retainer 145, while its inner race 147 is integral withthe annular flange-like retainer 150. Thus, the balls 149 of ballbearing system 154 act with races 146, 147 to absorb the transientupward thrust and generally to position the shaft. When the entireapparatus is operating, the shaft is in a downward position and retainer150 is not rotating, there being clearance between it and surface 148.

Normally, the start cycle is a small fraction of the expected life ofball bearing system 154 under the circumstances. As rotational speed ofthe apparatus increases, the downward thrust of the pump will exceed thehot well water upward thrust, and the sense of the thrust on the shaftreverses. It will be understood by those skilled in the art thatsufficient axial clearances are provided throughout the invention thatthe shaft, together with its attached turbine and pump rotors, will thenmove downward, disengaging contact between the end surface 148 of shaftportion 94 and retainer 150, disengaging the ball bearing system 154.Thus, under normal operating conditions, bearing 154 is unloaded and thefriction ring 153 acts to prevent incidental rotation of inner race 147and ring 150.

As noted in the foregoing, a hydrostatic thrust bearing as shown in FIG.14 may replace and play the role of the hydrodynamic thrust bearingillustrated in FIG. 9. Such a hydrostatic thrust bearing may be usedcooperatively with a pair of radial pad bearings of the type shown inFIG. 9, only one such bearing being shown at shaft portion 58 in FIG.14.

The hydrostatic thrust bearing of FIG. 14 is also lubricated by cleanwater flowing through passage 73a and consists of rotor and stator partslocated in a generally cylindrical cavity 152. The stator 158 surroundsshaft portion 142 with a small clearance passage at 160 of width, forexample, 0.002 inches, and is pressure balanced against the non-rotatingbody casting block 74. Although not actually prevented from rotating,the friction between bearing stator 158 and block 74 is sufficient toprevent stator 158 from turning with shaft portion 142. The bearingrotor 159, which is pressure balanced against the hub 49 of the steamturbine wheel, generally rotates with hub 49. Both the stator 158 androtor 159 are permitted to move axially relative to shaft portion 142 byslight amounts. Thus, stator 158 and rotor 159 can move axially relativeto each other by amounts sufficient to bring their spherical bearingsurfaces into natural alignment for supporting a lubricating water filmat 141, water for the film being supplied from passageway 73a throughannular passages 162, 163, 157, 160, and 161. The hydrostatic pressureunbalance caused by any non-alignment of bearing stator 158 and bearingrotor 159 forces the parts into alignment. The passage 157 includes anannular pressure-dropping seal 156 held in position by retainer 155.

In operation, the high pressure lubricating water flows past pressuredropping seal 156 and across the spherical bearing surface, forming film141, and is conveniently disposed of in the low pressure steam turbineexhaust passage region 56. If the pressure of the lubricating waterappoaching seal 156 is, for example 1400 p.s.i., part of this willappear as a pressure drop across seal 156, with most of the remainder ofthe drop appearing across the bearing interface within film 141. Thebearing 158, 159 is designed so that the average effective pressure inthe spherical film 141 acting to separate the components 158, 159generates an upward force substantially matching the downward thrust ofthe pump at the chosen operating bearing clearance of film 141 (say,0.0005 inches). This film thickness changes to match changing loadingconditions, increasing slightly with a decreased load and decreasingslightly with an increased load.

Such action obtains because the seal 156 provides a substantiallyconstant impedance, the pressure drop across it being proportional toflow rate, and the bearing impedance changes as the film 141 thicknesschanges, the pressure drop at the spherical bearing at constant flowrate being inversely proportional to the cube of the film 141 thickness.Accordingly, if bearing 158, 159 is operating stably in a steady statecondition and the load is increased:

a. the increased load becomes greater than the hydrostatic forcegenerated in the thrust bearing and the bearing clearance begins todecrease,

b. as the clearance decreases, the thrust bearing impedance increasesand water flow through the seal 156 accordingly decreases,

c. with decreased water flow, the pressure drop across seal 156decreases and the drop across the bearing increases, and

d. the bearing continues to close down until the pressure across thebearing rises to the point that it supports the increased load. If theload diminishes, the reverse sequence is experienced, the bearingreaching equilibrium with an increased clearance and increasedlubricating water flow.

In discussing the apparatus of FIG. 15, it will further be understoodthat the objective of the deep well apparatus of FIGS. 1 through 14 isto serve as part of a system to generate large quantities of electricpower at the earth's surface using generally conventional steam turbinesand electrical generators preferably located at ground level, such assteam turbine 260 and the electrical alternator 261 of FIG. 15, at poweroutput terminals 262. For this purpose, the hot water pumped to theearth's surface is fed by pipe 10 and its extension (pipe 10a) throughthe normally open valve 264 to element 266 of the conventionalboiler-heat exchanger device 265. Device 265 is of conventional closedtank-like nature and is designed to exchange heat between the heatexchanger elements 266 and 271 contained therein. The elements 266 and271 may take the form of lineal or coiled pipes exchanging heat energyby direct thermal conduction through their metal walls or through asuitable interposed fluid in the well known manner. Heat from the hotwater of pipe 10a is the major source of heat for supply to device 265.A small portion of the hot water, having been relatively dropped intemperature within boiler-heat exchanger 265, is then fed via pipe 267through the normally open valve 268 to the conventional evaporator 269.Valve 268 may be a throttle valve adjusted for the purpose of droppingthe pressure of the fluid flowing through it so that the fluid willreadily flash at low temperatures when supplied to evaporator 269.Evaporator 269 is of conventional nature and is supplied in the usualmanner with a conventional vacuum pump 270 which serves to remove thenon-condensable gasses.

Evaporator 269 generates clean steam which is condensed by theconventional condenser 273 and is supplied by water pump 272 at junction274 for augmenting the clean water supply. The major portion of thewater originally flowing upward in the well casing pipe 10 is returnedby pipe 275 to the earth well formed by pipe 277. Thus, a major portionof dissolved mineral salts pumped to the surface in solution in the hotwater in pipe 10 is returned into the ground. The well formed by pipe277 may be reasonably remote from the well of the thermal well systemand may serve more than one such system. It may pass the liquid into anearth stratum differing from the original hot well water source or intothe same strata. An accumulator or variable capacity storage tank 185 isadded in a branch line 8a connected to clean water return 8 for purposesyet to be described.

A second source of energy is supplied to boiler-heat exchanger device186 and is the steam exhausted from the deep well turbine 5 via pipe 9.This steam is permitted to flow through pipe 9a and the normally openvalve 278 to the heat exchanger element 187 of boiler-heat exchangerdevice 186. Element 187 is arranged so that the steam therein is exposedto thermal interchange at the coolest end of device 186 (adjacent thecool clean water input to heat exchanger element 188). Accordingly, theexhaust steam from pipe 9 and 9a is condensed within heat exchanger 186.The water thus condensed is supplied through pipe 279 and the normallyopen valve 280 to the aforementioned junction 274. The water from pipe279 and that from condenser 273 arrive at junction 274 in relativelypure state and may therefore be supplied directly to the cold waterinput pipe 8 of the deep well apparatus. With valve 281 in branch line282 closed, the water at junction 274 is fed by a conventional feed pump283 through the normally open valve 284 and pipe 8a into pipe 8.Replenishment water may be supplied by opening the valve 281 from anyavailable source coupled at terminal 297. It will further be understoodthat condenser 273 may be water cooled, as by supply of cool water froma cooling tower (not shown) to heat exchanger element 286 in heatexchanger 273. Alternatively, element 273 may be cooled in manylocations simply by forced air flow.

The feed pump 283 is transformed, in effect, into a variable flow pumpby the use of adjustable valve 305 placed in shunt with the pump or byother well known means. Accordingly, the amount of clean water passingthrough the clear water return pipe 8a may then be adjusted to anoptimum value manually by adjustment of valves 284 and 305 from apreviously prepared table upon visual inspection of the readings ofindicators 180 and 181, respectively showing the pressure andtemperature of the pumped hot well water within pipe 10. A servo systemmay be employed to perform the adjustment, if desired.

During normal turbine-pump operation, the feed pump 283 delivers cleanwater to the downward flow feed pipe 8 at a pressure that is sufficient,considering the gravity head, that the clean lubricating water arrivesat the input to the subterranean steam generator 18 at a pressureseveral hundred pounds per square inch above the pressure of the hotwell water. The accumulator 185 then operates to smooth any pressurefluctuations which might otherwise occur due to pump 283 at the input tosteam generator 18.

Threshold valve 15a of FIG. 2, shown also in greater detail in FIG. 16,is set to open at a fixed differential pressure (say, 100 p.s.i.) abovethe hot well water pressure and is thus normally wide open. Thedifferential pressure valve 15b, also seen in FIGS. 2 and 16, is presetso as to maintain automatically a constant differential between thepressure of the feed water and that of the water entering steamgenerator 18. The steam generator input feed water pressure must be lessthan the saturation pressure of that water at well temperature in orderthat it may vaporize within the steam generator 18. Under properoperating conditions, the steam generator input water pressuredetermines the pressure within steam generator 18. Further, the steampressure determines the rate of mass flow through turbine nozzles 59.

Thus, according to the invention, the feed water pressure is controlledat the surface by varying the feed pump 283 output pressure into pipes8a and 8. Only one simple element is involved in the control operationthat must be located near the deep well apparatus. As will be seen, thesteam exhaust pressure at turbine 5 is controlled from the surface byadjusting its condensing temperature. Such a control permits control ofthe dryness of the steam within turbine 5.

The turbine-pump system may be shut down by lowering the output pressureof clean water feed pump 283 to the point at which threshold valve 15acloses, but still at a pressure sufficient that the turbine bearings arelubricated while the stored energy in steam generator 18 is dissipatedand the rotation of the turbine ceases. This intermediate pressure isstill above the pressure of the hot well water and may be maintainedcontinuously while the rotary system is stopped so as completely toexclude the hot contaminated well water from the interior of theturbine-pump system and particularly from the interior of all bearings.

The valve 284 may include a check valve mechanism as well asconventional flow rate adjusting parts. If the feed pump 283 fails, sucha back flow check valve will shut, preventing flow loss through feedpump 283, and the pressure within accumulator 185 will quickly decay tothe level at which threshold valve 15a closes. Thus, the turbine 5 maysafely decelerate and stop. Accumulator 185, however, will continue tosupply the small clean water flow required by the bearings of thepump-turbine system for lubrication of all bearings during the stoppingsequence.

Referring now to FIG. 16, details of the threshold valve 15a and thedifferential pressure valve 15b of the regulator 15 are presented. Aspreviously noted, the pressure regulator system may compriseconventional elements. These elements may be enclosed in a unitaryextension of the clean water input pipe 14, the extension being coupledat its lower output to the distribution pipes 16 previously discussedwith respect to FIG. 2. Also supplied is a tube 21 for coupling thepressure of the rising hot well water to the threshold valve 15a.

It is seen that the threshold valve 15a utilizes a valve armatureelement 202 which may seat in an annular conical seat in partition 201with the cooperative guidance provided by guides 200 and a stem 205 freeto move vertically within a cavity 206 provided by damping purposes, ifdesired. The armature 202 of the valve 15a is further supported by aspring bellows 203, sealed to the base of the armature 202 and to thetop of a cup element 204 surrounding damper element 206. Tube 21provides support for cup 204 and an input to the cavity formed withinbellows 203, cup 204, and damper cavity 206 so that a pressure ismaintained therein corresponding to that of the rising hot well water.

The pressure above armature element 202, when threshold valve 15a isopened, is communicated through cavity 207 to the top of a second valvearmature 210 found within differential pressure valve 15b. The armature210 is arranged to seat against a conical surface in the partition 209,being guided with respect to the aperture in partition 209 by guides208, stem 212, and piston 213. Piston 213 may operate as a damperelement by employment of a suitable damping fluid in cavity 214 alongwith a small bore 213a communicating between opposite surfaces of piston213. Operation of the differential pressure valve 15b, like that of thethreshold valve 15a depends upon use of an appropriate spring constantfor the spring 211 which tends to urge the valve armature 210 intoseated relation with the conical seat of partition 209. In view of thegenerally conventional nature of the elements of this regulatory system15 and considering its function in operation within the system as awhole as described in the foregoing material, its operation will befully apparent to those skilled in the art.

The major elements for supply of heat into boiler-heat exchanger device265 have been described. This heat is removed and used in asubstantially conventional manner to operate the surface-located vaporturbine 260. For this purpose, liquid is supplied by a conventional feedpump 288 via pipe 289 to the heat exchanger element 271 of boiler-heatexchanger 265. Flow of the liquid is counter to the direction of flow ofheat into device 265 in element 266. The liquid evaporates andconsequently generates high temperature vapor that is coupled via pipe290 to the input stage of turbine 260. After performing useful worktherein, the turbine exhaust vapor fed by pipe 291 flows to aconventional condenser device 293 having heat exchanger elements 292 and294 and then flows again as a liquid via pipe 296 to the feed pump 288.Condenser 292 may be cooled by flow of water from a cooling tower (notshown) through heat exchanger element 294. The exchanger 293 mayalternatively be air cooled in the conventional manner. A fluid such aswater may be used for the generation of high temperature vapor withinboiler-heat exchanger 265 and its associated surface-located loop orcertain organic fluids affording best use in Rankine cycle operation mayalternatively be employed.

Referring again to FIG. 15, there is located between feed pump 288 andcondenser element 271 a variable valve 190 in shunt with heat exchangerelement 188. The valve 190 may be adjusted manually after observation oftemperature indicator 189 which provides a reading in response to thetemperature of the turbine exhaust steam in pipe 9a. An automatic servolink indicated by the dotted line 191 may alternatively be employed.By-pass valve 190 is continuously adjusted according to the temperatureof the steam in pipe 9a. Thus, the pressure in pipe 9a (the subterraneanturbine 5 back pressure) is adjusted so as to control the dryness of thesteam in turbine 5. This desired control is readily exercised at thesurface simply by adjusting the temperature of condenser 186.

The general operation of the invention will be apparent from theforegoing description. It is seen that the geothermal energy deep wellsystem consists of a deeply submerged super-heated steam generationsection 4, a turbine section 5 driven by the super-heated steam, and ahot water pumping section 7 all located in a hot water source regionwhere there is present large quantities of hot water which may alsoinclude relatively large quantities of dissolved materials. Clean water,formed by condensing the clean steam at the surface, is supplied to thesteam generation section 4 for driving the turbine at 5 and is alsoreliably supplied to bearings in the turbine and pump sections thereof.The hot water pump section 7 serves to increase the pressure level ofthe hot water so that it reaches the surface of the earth still wellabove its saturation pressure.

The pressure of the well water entering the hot water pump is greatenough to prevent cavitation damage to the pump and any consequentperformance loss in the pump. In general, it is arranged that actualpressures in the hot water are maintained above the flash point by awide safety margin at all points in the hot water flow system within thewell. This is one of the several features of particular importance tothe success of the invention, since the hot water can not flash intosteam when held at all times and locations above its flash pressure.Flashing of the hot water into steam is to be prevented, since it islikely to be disruptive if not actually destructive of equipment and atleast will result in the deposition of large amounts of mineral scale inthe general location of the flash event. The system at the surface ofthe earth readily extracts heat from the extremely hot water for thegeneration of electrical power or for other useful purposes. What energyremains in the steam used to drive the deep well turbine at section 5 isalso returned to earth's surface for recovery in the surface-locatedsystem.

While the invention has been described in its preferred embodiments, itis to be understood that the words which have been used are words ofdescription rather than of limitation and that changes within thepurview of the appended claims may be made without departure from thetrue scope and spirit of the invention in its broader aspects.

I claim:
 1. In geothermal deep well pump apparatus of the kind includingpump means for pumping a first fluid always in liquid state for flow incooperative energy exchanging relation with respect to a secondfluid:first, second, and third conduit means respectively fortransmission of said first and second fluids and a third fluid andhaving first common wall means between said first and second conduitmeans and second common wall means between said second and third conduitmeans,said first and second common wall means being disposed one withinthe other in substantially vertical concentric relation, said firstfluid being hotter than said second fluid and said second fluid beinghotter than said third fluid, and deflector means within said secondconduit means for urging said second fluid into effecient proximatethermal energy exchange relation with said first common wall means andaway from said second common wall means.
 2. Apparatus as described inclaim 1 wherein said deflector means comprises curved vane means pendingfrom at least one of said first or second common wall means forimparting a component of rotational motion to said second fluid forincreasing its proximity to said first common wall means therebyimproving heat exchange between said first common wall means and saidsecond fluid while diminishing heat exchange between said second commonwall and said second fluid during passage of said second fluid throughsaid second conduit means.
 3. Apparatus as described in claim 2 whereinsaid second fluid constitutes a dual phase fluid including liquid dropsand vapor for at least a portion of said passage through said conduitmeans.
 4. Apparatus as described in claim 3 additionally including:pumpmeans coupled to said first conduit means for pumping said first fluidin the form of hot geothermal water therethrough, motor means coupled tosaid pump means and responsive to said second fluid in the form of steamfor driving said pump means, and motor exhaust means for coupling saidthird fluid in the form of exhaust steam into said third conduit means.